During refueling, it is possible for water to be pumped into your fuel tank along with the diesel fuel. Your vehicle has a water separation system in the fuel filter.
It also has a “WATER IN FUEL” light in the instrument cluster which is designed to come on if water has accumulated in the fuel filter and if the fuel filter becomes plugged (a low pressure sensor will activate the light). (The “WATER IN FUEL” light is also designed to come on during engine starting to let you know the bulb is working. If the light does not come on, check the fuse and the bulb.)
The G & P Truck have a remote mounted water drain valve near the water outlet.